The transportation of cargo between destinations on the Earth's surface has been expensive, but these costs have been overcome with time, and mature transportation markets have emerged. Container freight has, for example, recently solved the disconnect between the ocean and land travel vehicles. In New York Harbor, longshoreman, for example, would extract an unannounced tax of about 10% on Irish Whiskey by losing some whiskey in the unloading process. Containers now accelerate the cargo transfer from ocean to other forms of transportation vehicles with less chance for loss and less manpower. The harbor is also convenient for the sale of other transportation services like fuel as well as other unrelated commercial services. Eventually harbors grow beyond transportation related services into locations of commerce with transportation services as one of many industries within a city.
The transportation from the earth's surface to destinations in space is currently expensive. All or most business ventures in space start with transportation, so the high cost of transportation slows the growth of commercial space. The high transportation cost creates a barrier to travel and to the commercial development of space by stifling the investment of private capital in technically viable ventures on the emerging economic frontier of space.
Part of the problem is transportation to orbit requires a transportation vehicle that operates in both the atmosphere and the vacuum of space. The traditional rocket punches up through the atmosphere and operates successfully in orbit. Some stages or sections of the rocket are expended and discarded in the trip to reduce the mass and permit the mission to attain orbit.
Discarded elements are something to minimize in space transportation, partly because it takes the discarded elements nine times the mass per pound, to move the mass to Earth orbit, up through the gravity well of Earth. Once the mass is transported up through the gravity well, then the transportation investment has been made for that mass and the mass takes on an invested value equal to somewhere between zero, in the case of useless mass with no second use in orbit or elsewhere in the universe, to as much as $10,000 to $25,000 per pound, in the case of mass transported to orbit by the space shuttle that can find a secondary use or a reprocessed use in space.
Air travel in the atmosphere is common and relatively inexpensive. After over 100 years of aircraft development experience, the commercial air travel environment is diversified, deregulated and in need of an innovative shot to move into the 21st century. A solution that captures the market and still attacks the high cost of transportation would be ideal. Mankind can learn from history and bring the aircraft and space transportation innovation together.
Two problems to which the present invention is directed include safety and capacity.
Safety: Launch systems with cryogenic propellants and high speed rotating machinery are fundamentally unsafe systems. Most of this space launch hardware is technically complicated partly due to the fact that it is designed to work in two environments. First, the space launch vehicle operates as it climbs out of the gravity well and in atmosphere that varies from sea level to orbit. Second, the same vehicle operates in the vacuum of space with no gravity well. The same vehicle is designed for both environments and may be more expensive as a result. Individual more efficient vehicles designed for each of the vastly different environment may be more economical.
Capacity: A specific launch system has a payload capacity to support a narrow variety of missions. Rockets capable of overcoming the gravity well of Earth, need to be 90% propellant and 10% other mass, like tanks and payload, or they do not launch. Most Expendable Launch Vehicles (ELVs) are built vertically or one item at a time on the pad. Payloads are further complicated by the requirements to fit into the specific partly reusable vehicles. Both issues significantly drive up payload costs. Transporting the propellant needed for a trip to Mars on a Mars vehicle launched from Earth is an unrealistic burden for the vehicle. A propellant depot beyond the Earth's surface could help this situation.
Huge economic benefits might be realized if a launch system could be developed that had significant atmospheric travel applications and could make the transition to space as required. Propellant depots could provide services to such Trans-Atmospheric vehicles, whose ultimate destination is another location on Earth.
U.S. Pat. No. 4,699,339 to Rosen, entitled “Apparatus and Method for Transporting a Spacecraft and a Fluid Propellant from the Earth to a Substantially Low Gravity Environment Above Earth,” discloses an invention that includes separating propellant mass from the final propellant tankage in an attempt to reduce the final fluid tank structure weight of the final satellite or deep space mission, where excess mass causes problems and expense. While in U.S. Pat. No. 4,699,339 some propellant is suggested to be transferred in orbit, it does little to focus on the economics of reusable tanks, but suggests two tanks for the same fluid with one being heavy and designed for launch loading requirements and a second tank carrying nothing through the difficult launch phase, so as to minimize the second tank's mass in space.
There is a need to eliminate the requirement that the entire space transportation operation originate on Earth's surface. In simple terms, eliminating this requirement would allow more efficient space transportation vehicles to be used in each transportation cycle between propellant depots or nodes.